火干扰对次生林森林土壤斥水性的影响机制

Recent years witnessed global climate anomalies, frequent forest fires, forest area decreased and serious secondary disasters. Along with attention to forest fire prevention and forest ecosystem health protection, the repairment of the forest structure and productivity and the restoration of ecological function of forest soil also become the most urgent problem to be solved.Therefore, The main secondary forests woodland in south were selected as the object, fire disturbance test was implementated.A study on soil water repellency and the restoration of the ecosystem of forest soil after fire disturbance is of great theoretical and practical significance.With the forest ecosystem health management as the theoretical basis, and starting from the relationship between the structure and function of forest soil, this research uses the system diagnosis, fractal theory and wavelet analysis technology to study the influence of fire disturbance on the changes of physicochemical properties on the southern forest soil, and to analyze the fire disturbance mechanism influencing water repellency of space-time of forest soil. In this research, the relationship model of soil water repellency and soil properties is to be constructed, forest soil water repellency rating standard is to be set up, improvement of post disaster soil water repellent is to be analyzed, soil improvement methods is to be determined, the effects of improved soil water repellency is to be evaluated, different spending improved scheme is to be selected. This research provides guidance upon soil improvement after forest fire, as well as theoretical basis for vegetation restoration of burned areas.

近年来，全球气候异常，森林火灾频繁，森林植被面积减少，次生灾害严重。在重视森林防火和保护森林生态系统健康的同时，如何修复林地结构和地力，恢复森林土壤的生态功能成为当前最为迫切需要解决的难题。因此，以南方主要次生林林地为对象，进行火干扰试验，开展火干扰对土壤斥水性的影响机制及森林土壤生态系统修复的研究具有重要的理论意义和实践指导作用。以森林生态系统健康经营为理论依据，利用系统诊断、分形理论和小波分析等技术手段，从森林土壤结构与功能的关系出发，研究火干扰对南方次生林土壤的理化性质变化规律，分析火干扰对森林土壤斥水性的时空影响机理，构建土壤斥水性与土壤性质的关系模型及土壤斥水性预测模型，制定森林土壤斥水性等级标准，进行灾后斥水土壤修复的需求分析，确定土壤修复方法，对斥水土壤修复效果进行评价和不同斥水程度的土壤修复试验进行选优，指导森林火灾后土壤修复，为火烧迹地植被恢复提供理论依据。

近年来，全球气候异常，森林火灾频繁，对土壤生态系统造成巨大影响，如何修复火烧迹地土壤结构、地力和功能成为当前最为迫切需要解决的难题。以杉木与木荷混交林、马尾松与木荷混交林、檫木与杉木混交林及枫香次生林为例，开展如下研究：. （1）火干扰对土壤的理化性质变化规律：随土层深度的增加，火干扰强度对土壤容重、pH、有机碳、全N、全P、全K 的含量的影响逐渐减弱。其中，火干扰对土壤表层0-5cm 和6-10cm 土层土壤理化性质的影响极显著（p＜0.05），对11-15cm 和＞15cm 土层的理化性质影响不显著。4 种林分类型0-10cm 土层土壤理化性质指标在高度和中度火干扰与无火干扰间差异显著（p＜0.05），而轻度火干扰与无火干扰间差异性不显著。随着火干扰强度的增加，土壤容重和pH 均有显著增加，而土壤有机碳、全N、全P 和全K 的含量均有显著性减小。. （2）火干扰对森林土壤斥水性的时空影响机理：火干扰强度越大，土壤斥水性越大，但随火后时间的推移，土壤斥水性逐渐下降，尤其是在火干扰后90天内下降的速度最快，而在火干扰180天后土壤斥水性在不同火干扰间的差异性不显著。. （3）构建土壤斥水性与土壤性质的关系模型：不同林分类型土壤斥水性与土壤理化性质指标的典范相关指标不同。构建了4种林分类型不同火强度干扰后土壤斥水性与土壤理化性质关系模型一套。. （4）土壤斥水性预测模型：对4 种林分类型土壤理化性质指标进行综合评价，对4种林分土壤理化性质综合评价值和斥水性进行拟合，构建土壤斥水性与土壤理化性质综合评价值之间的相互关联模型，为火后土壤斥水性预测提供支撑。. 本项目开展火干扰对南方典型次生林土壤斥水性的形成机理、多因素联合时空变异规律、土壤斥水性预测模型等研究，为森林火灾后土壤修复和植被恢复提供理论依据和实践指导，对减少灾后水土和养分流失具有一定的应用价值，对巩固生态文明建设成果及促进区域经济发展具有重要意义。